could be one of many factors: are the plants being fertilized properly? if you are growing them for seed make sure that they are receiving all nutrients + micronutrients. Check what the leaves look like and post back (are they droopy, yellow, spotted, brown, straight out, etc.) plants tell us everything with their leaves. another possibility would be stress, or maybe the light cycle is being interfered with. also seeds do take time to mature so it may just be taking its time. If you are very concerned with mold perhaps you could rig up a tarp system if that is not a security concern? anyways i hope this was of some help